Stationary bikes provide great exercise and are popular options for those who like to exercise at home. It is not difficult to spot and fix problems with your stationary bike when you know what to look for, and they tend to have few problems when kept clean and lubricated. However, every stationary bike model is different, so refer to your owner's manual for instructions on how to fix specific issues with your bike.
Clean and lubricate the gears that control the resistance/intensity mechanism of the stationary bike. This should fix bikes that do not change intensity settings easily. Follow the lubrication manufacturer's instructions to be sure that you fix this problem properly. Any professional lubricant brand and type will work well for this task.
Check for a wobbly resistance wheel and replace the hub if your bike has this issue. Change the hub by loosening the resistance machinery and removing the wheel and hub bolt with a wrench. Then take off the old hub and put in a new one. Put the hub bolt and wheel back into place and tighten the resistance mechanism.
Keep the chain clean. A dirty and dry chain is noisy and makes the bike hard to ride. Use a rotating brush chain-cleaning tool to clean the chain.
Replace worn pedals. Change the pedals when they are not at 90 degrees to the crank arm. Change the pedals if you feel a bump in the pedal stroke, too. Remove the pedals with a pedal wrench and put new ones in their place.
Remove the handlebars and seat and clean them well. Use 1200-grit sandpaper to build up the grips. This will ensure that your hands won't slip when you sweat.
Keep your bike clean and lubricated to avoid having to make future repairs.